3D PRINTING: UNIT PLAN PROPOSAL

A. Guerrero-de-Mier1, M.M. Espinosa2, M. Dominguez3 1,2,3Universidad Nacional de Educación a Distancia (SPAIN)

Abstract

In this paper we propose the methodology for conducting a pilot studio of 3D printing in high school classrooms. We will use Azara RepRap printers, a model developed by ourselves that needs no external computer.

We suggest several possible projects, their goals, their basic content and key competences covered, their evaluation criteria and the basic content of the satisfaction surveys.

Keywords: 3D printing, unit plan, RepRap.

1 3D PRINTING

3D printing process is based on the Dispersion-Accumulation Principle. Objects are modelled in three dimensions using CAD programs, and then the objects are sliced into thin layers, which are subsequently built and stacked in order to form the original shapes (fig 1) [1].

Currently, the most used technology is Fused Deposition Modeling (FDM). In this technology thermoplastic materials are used, such as ABS (acrylonitrile butadiene styrene) or PLA (polylactic acid). The thermoplastic material is heated, melted and extruded through a nozzle to build the 3D object. This technology was developed in 1988 by Stratasys Inc. It's a low cost technology, less accurate than other like stereolithography or laser sintering, and built objects can suffer deformations when it cools.

The RepRap initiative was founded by Adrian Bowyer at the University of Bath in 2004[2]. This initiative has achieved success in designing and building many low cost 3D printers, published under the “Do It Yourself” philosophy. These printers are partially self-replicant and they are registered under a GPL version 2 license, so they are Open Source. RepRap printers uses Fused Deposition Modelling (FDM)TM technology.

Figure 1. Dispersion-Accumulation Principle

2 UNIT PLAN GOAL AND CONTENTS

We propose the establishment of a unit plan consisting in the implementation of two projects, based on the Project Based Learning methodology (PBL).

We propose two consecutive projects:

- Assembly of 3D printer.

- 3D models design and printing. In fact, this project represents a variety of different projects.

The workflow of projects is included in figure 2.

BASIC

TRAINING

(3D PRINTING)

START OF PROJECT

3D MODELING

AND

PRINTING

SURVEYS

(Pretests)

SECOND

TRAINING

(3D MODELING)

SECOND

TRAINING

(3D PRINTER

ASSEMBLY)

3D PRINTER

ASSEMBLY

COST STUDY

MARKETING

CAMPAIGN

TRIALS

FINAL

PRESENTATIONS

END OF PROJECT

SURVEYS

(Postests)

Figure 2. Unit workflow.

2.1 Basic training

The first step in projects is to conduct a basic training on 3D Design and Printing. The contents of that basic training are:

1. Principles of 3D Printing: How it works and different technologies in 3D printing, especially Fused Deposition Modelling (FDM)

2. Models of FDM 3D printers, with emphasis in the RepRap printers

3. Basic operation of 3D printers

Once the basic training is ended, students can start with

2.2 Assembly of 3D printer

This project consists in the assembly of a 3D printer kit. The final goal is to obtain a functional, calibrated and tested 3D printer, which can be used in later projects.

The first step in this project is to conduct a second training. The contents of that second training will be the following:

1. 3D Printer parts

2. Features of the selected 3D printer kit

3. Explanation of the assembly of the 3D Printer kit.

After training, the students will be divided in working teams. The 3D printers can be divided in the following parts:

- Chassis

- Axis X, including carriage

- Axis Y and Z

- Printing Bed

- Extruder

- Electronics

There are two options:

a) Each team will assemble one or more of the mentioned printer parts, or

b) Printer parts could be assembled and then disassembled, so each team could assemble the whole printer.

The students will write the instructions of the assembly of each part, including the necessaries pictures and plans. Furthermore, students will create a presentation with slides, video, etc

The teacher could assemble the electronics, if he thinks that students will not be able of make it.

After the assembly, one of the students' team will install the printer firmware (the software resident in the machine) and will calibrate it.

2.3 3D Models Design and Printings

The second project consists in the design, modelling and printing of 3d models. The teachers will select the model's goal, in function of the subject's goals (or other subjects' goals, like Biology, History, etc)

We suggest possible models' goals:

- Making a model of singular buildings in high school district or town. Each student's team will draw schemes of a singular building, modelling different parts and printing them. Students could use paper pictures and glue, moreover the printed parts. Furthermore, the teams will write the history of the building (designer, builder, former and actual use, etc)

- Design and construction of a scaled bridge, including foundations, support elements and bridge deck. Each student's team will select and existing bridge, finding its features in internet. Then they will

model and print the main parts. Finally, using metal cables, glue and printed plastic parts, the teams will build the bridge. Furthermore, the teams also will write a report with the technical features of the real bridge, and the basic operation of the bridge's structure.

- Vehicle design. Each student's team select a type of mobile vehicle (bike, car, robot, tracked vehicle, etc), modelling and printing the basic parts of the vehicle structure. Then, the teams will build the vehicle using plastic parts, glue, and several accessory parts (like cables, screws, nuts, etc). Furthermore, the teams will write a report explaining the vehicle's features.

- Making a model of a world famous monument. Each student's team will select a world famous monument (Eiffel tower, Pisa tower, Liberty Statue, etc), finding its features in internet. Then they will build a scaled monument, modelling different parts and printing them. Students could use paper pictures and glue. Furthermore, the teams will write the history of the monument (designer, builder, former and actual use, etc)

- Sculpture competition. Each team will design, model and print a different sculpture, on a given particular topic, selected by the teacher. Furthermore, teams will write a report explaining the relation of its structure with the selected topic.

We recommend the use of a free application, like:

- FreeCAD, an open source parametric 3D CAD modeler, for Linux, Mac OSX and Windows.

- Autodesk TinkerCAD, a free and easy-to-learn online application. This application only needs an internet connection and a HTML5 compatible web browser. It can run on any operating system (Windows, Mac OSX, Linux, etc).

- Autodesk123D Design, a free 3D creation and editing tool, for Apple iOS, Mac OSX and Windows.

- Autodesk 123D Sculpt+, a free app to create 3D sculptures, for Apple iOS and Android.

- Trimble Sketchup Make, a 3D drawing tool for Mac OSX and Windows, free for educational use.

At the start of the Project, teacher will conduct a basic training on 3D Design & Printing, with the contents mentioned above, following by training on modeling in 3D.

The contents of that second training will be the following:

1. Principles of 3D Modeling

2. Basic operation of the selected 3D modeling application. Basic geometric figures. Importing & exporting.

3. Complex parts

4. Slicing & printing

After the second training, the students will be divided in teams. Then, the teams will choose their object to model, concerning project goal. They will model, print and build the object, and finally they will write the report and the presentation.

Students could use their own computer or tablets, or they could sketch models and take turns using the school computers.

3 REPRAP AZARA

We propose to use a RepRap Azara 3D Printer, a RepRap improved variant with an electronic controller based on a Beaglebone open source 32 bits minicomputer. That printer is able to process 3D models alone, without any external computer, and to communicate through a web interface (fig 3) with printer's users. It can be used remotely or through the local area network of the educational institution, and can be handled by a smartphone, a tablet or a computer [3].

However, teachers could choose any other 3D printer. There are many different models: commercial or open source, assembly kits or mounted printers. For example, a complete 3D printer assembly kit could be bought for less than 500 € in a lot of web shops.

Figure 3. Web interface of RepRap Azara

4 END OF THE PROJECT

After building a 3D printer or 3D models, the teams will perform the following phases:

- Cost study

- Selling the product

- Trials

- Final presentations

4.1 Cost study

The goal of this phase is to calculate the manufacturing cost of the built product in the project: 3D printer or 3D model.

In the first case, cost will be given by 3d printer kit cost, labour and consumables cost.

In the second case, cost will be given by the following parts:

- Plastic used: students will have to calculate the volume of plastic used in the models.

- Energy

- Printer depreciation

- Labour cost of design and modelling.

Finally, the students could obtain the final selling price of the model or printer, adding a benefit percentage to the calculated cost.

4.2 Selling the product

The goal is to conduct a virtual sales campaign. To that end, students will design a marketing campaign, with brochures, advertisements, etc.

The marketing campaign will be exhibited in the education centre, and hard copies will be sent to students' families.

4.3 Trials

In this phase, teams will practise their presentations in front of the class. The students will grade the presentations, reflecting their faults, rating separately:

- Presentation contents

- Verbal expression

- Body language

The ratings will be discussed in public, to enforce the social interaction among students. They will also learn to master their fear of speaking in public, to manage group dynamics, and became more articulate in their presentation.

4.4 Final presentations

Finally, after testing once or twice, all the teams will make their final presentations.

The event should take place in a large hall, and the students' families should be invited to attend the event, to promote the family involvement.

5 KEY COMPETENCES OF THE UNIT PLAN

The key competences developed by the Unit Plan will be the following:

- Linguistic competence: The different projects include writing any report: instructions, history of buildings or monuments, features of model, etc. Public presentations and discussions within the team improve speaking and listening, and reports and marketing campaigns improve writing and reading.

- Mathematical competence and basic competences in science and technology: Students need improve their mathematical competence to model in 3D. They will have to measure, calculate and develop 3D vision to be able to make 3D models. Mathematical competence is also improved by the use of geometric models and the understanding of surfaces and volumes. Basic competences in science and technology are improved by the printer assembly. Students learn about engines, motion transmission, sensors, etc.

- Digital competence: Students will have to use several complex applications to finish the projects. They will have to modelling, make presentations, design brochures, etc. Teachers must encourage all students to use the computer.

- Competence in social skills and citizenship: Teamwork promotes social interaction among students, improving their social competence. Team members have to reach agreements, what improve the peaceful resolution of conflicts and social interaction.

- Cultural expression: Presentations, brochures and some of the project models (sculptures, monuments, …) improve the cultural and artistic competence.

- Learning to learn: It is promoted mainly by trials before the final presentation, due to public discussions and grades. Students will learn of their own classmates how to improve their skills.

- Sense of initiative and entrepreneurship: It is improved by the prices and costs calculation, and the design of the marketing campaign.

So, our unit plan covers all key competences established on the curricula for Secondary Education in Spain [4]

6 EVALUATING THE PROJECT

An evaluation will be carried out through two independent methods:

1. Student grades. These grades will be compared with average grades of previous years in the same subject and in the same education centre. If possible, the grades will be compared with average grades in province or autonomous region.

2. Satisfaction surveys. Statistical analysis will be carried out based on student, teachers and families surveys.

6.1 Grades

The teachers will evaluate separately each one of the following skills:

- Reports: to evaluate linguistic competence

- Quality of the 3D model: to evaluate mathematical

- Skill in the use of computer: to evaluate digital competence

- Presentations and marketing campaign: to evaluate linguistic and artistic competence

- Ability to function as a team member, and personal involvement in the discussions, inside and outside the team, to evaluate social competence and citizenship.

The weight of each partial grade will be decided by the teacher.

6.2 Surveys

Two surveys campaigns will be launched, the first before the project's start (pre-test), and the second after the project's end (post-test).

The surveys will cover topics including, but not limited to:

- General satisfaction of students, families and teachers

- Family involvement

- Social harmony improvement among students

- Teachers' professional development

- Quality of training received

- Printer suitability in classrooms

- Educational possibilities of 3D printing

The surveys could be carried out through web-based tools, with a view to encouraging participation of families.

7 FUTURE PROPOSALS

Once the pilot studio has been completed, we will propose training courses to several regional teacher training centres, according with the following programme:

- 3D design and printing: Basic concepts.

- RepRap Azara printers: Assembly, start up and operation.

A 3D printer mounting kit would be delivered as part of the training course, to encourage teachers to use them in their classrooms.

Furthermore, we will develop a public database of methodological resources, which we will compile the results of projects carried out.

REFERENCES

[1] Guerrero-de Mier, A., Espinosa-Escudero, M.M. (2014). Progress in RepRap: Open source 3D printing. DYNA, 89(1). 34-38

[2] Bowyer A et al. (2011). Reprap: the replicating rapid prototype. Robotics, vol. 29, pp. 177-191.

[3] L. Romero et al. (2014). Additive manufacturing with RepRap methodology: current situation and future prospects. 25th Annual International Solid Freeform Fabrication (SFF) Symposium, University of Texas. Austin

[4] Ministerio de Educación, Cultura y Deporte (2015) Real Decreto 1105/2014, de 26 de diciembre, por el que se establece el currículo básico de la Educación Secundaria Obligatoria y del Bachillerato. BOE, 03/01/2015, pp 169-507.

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ISBN: 978-84-944311-3-5

Edited by: ScienceKNOW Conferences C.B.

September 2015

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3d Printing: Unit Plan Proposal

A. Guerrero (1), M.M. Espinosa (1), M. Dominguez (1)

(1) Ingeniería del Diseño. Universidad Nacional de Educación a Distancia - UNED

C/ Juan del Rosal, 12. 28040 Madrid.

(+34) 678 417 791. aguerreromier@gmail.com

1. Introduction – In this paper we propose a methodology for conducting a pilot studio of 3D printing in

high school classrooms. We will use Azara RepRap printers, a model developed by ourselves that doesn’t

need external computer. We propose the establishment of a unit plan based on the Project-Based

Learning methodology (PBL). We suggest several possible projects, their goals, their basic content and key

competences covered, their evaluation criteria and the basic content of the satisfaction surveys.

2. Unit Plan - We propose two consecutive projects: First, the assembly of 3D printer, and second, the

design and build of a 3D model, about a topic selected by teacher.

We propose to use a RepRap Azara[1], a RepRap[2] improved 3D printer. That printer is able to process

3D models alone, without any external computer. We propose the following phases in every project:

2.1. Surveys (Pretests) – A surveys campaign will be launched before the project's start. The surveys will

be validated and their level of reliability will be computed. The internal consistency index will be evaluated

through Cronbach's alpha.

2.2. Training on 3D Design and Printing – The teachers will conduct two training sessions:

a) Basic training regarding principles of 3D Printing and fused deposition modelling (FDM) printers.

b) A second training adapted to the project that will be conducted, with the following contents: assembly

of a 3D printer (for the 1st project), and 3D modelling software (for the 2nd project)

2.4. Practical work - The practical work is adapted to the project content:

a) 1st project: Assembly of 3D printer. The students will assemble, calibrate and test the printer.

b) 2nd project: It is based on the designing and printing of 3D models, about a topic selected by teacher.

Possible options are: local or famous monuments, a bridge, a vehicle, or a Sculpture competition.

2.5. Marketing - The goal of this phase is to design a marketing campaign to sell the products built in the

previous phase, including calculation of sell prices and manufacturing costs.

2.6. Trials and Final presentations - The teams will practice their presentations in front of the class. Finally,

after testing once or twice, all the teams will make their final presentations in a public event.

2.7. Surveys (Postests) - A surveys campaign will be launched after the project's end.

3. Key competences –.The key competences covered by the Unit Plan are: linguistic (reports),

mathematical, science and technology (3D models, printer assembly), digital (applications), social and

citizenship (teamwork), cultural (presentations, brochures and some models), learning to learn (trials) and

sense of initiative and entrepreneurship (prices and costs calculation, marketing).

4. Conclusions -The unit plan covers all key competences established on the curricula for Secondary

Education in Spain. We are going to develop this Unit Plan in two Educational Centres in Andalusia(Spain),

during the next program year.

5. References

[1] JL. Romero et al, Additive manufacturing with RepRap methodology: current situation and future prospects. 25th

Annual International Solid Freeform Fabrication (SFF) Symposium, Univertity of Texas. Austin. 2014

[2] A. Bowyer et al, Reprap: the replicating rapid prototype, Robotics (2011), vol. 29, pp. 177-191